Vacuum-tube cathode-supply circuit



Mayfi 1930. A. LEIB 1,757,318

VACUUM TUBE CATHODE SUPPLY CIRCUTI Filed Dec. 5, 1922 mow 9523 7451 BALLAsT p GEL: F) f M V\ VW\/W\/- "MA/MAM CATHODE W W V SUPPLY avwewtoz AUGUST LEIB 931 his flbtomu m/z/V L Patented May 6, 1930 UNITED sra'rss PATENT oFFics AUGUST LEIB, OF BERLIN, GERMANY, ASSIGHOR TO GESELLSCHAFT Fl j'l't DRAI-ITLOSE TELEGRAPHIE B. H. I-IALLESGHES, F BERLIN, GERMANY, A CORPORATION OF GERMANY VACUUM-TUBE GATHODE-SUPPLY CIRGUII Application filed. December 5, 1922, Serial No As is well known, there are connecting means for feeding wireless telephone receiving and sending apparatus from power lines, such as the usual 110 or 220 volt subscriber net work distribution wires. The necessary means for eliminating the noises such as those from commutator ripple or a fluctuating com ponent are assumed tobe also well known.

Two circuit arrangements have been proposed for use with cathode tubes comprising respectively a purely parallel and a purely series connection of the heating filaments.

The parallel connection of the filaments has not been accepted because, due to the high current consumption, the heating is not economical. This occurs because of the fact that with the parallel connection the total current taken from the lines is the sum of the currents of the various tubes, and all of the energy, represented by this current multiplied by the difference between the supply line voltage and the small voltage drop in the filaments themselves must be wasted in a resistance.

The series connection of the heating filaments gives the lowest current consumption, since the current taken from the supply lines is only that required for one filament and the energy to be wasted in regulating resistance is only that amount represented by that small current multipled by the difference between the supply line voltage and the sum of the voltage drops in all of the series filaments. However, it necessitates the construction of special devices which must carry the total potential it a heating filament burns through. For this reason, it is impossible to feed an apparatus constructed for a battery heating potential of about 6 volts from the power circuit which may be the usual 110 or 220 volt supply, in accordance with the principle of the purely series connection, because the total power line potential occurs at the grid-potentiometers and at the switches, causing the destruction of the apparatus within a short time. The grid potentiometers, being con nected in parallel with the filaments in order to provide means for connecting the cathode terminal of the grid circuit to the effective to midpoint of the filament, must be of rela 605,001, and in Germany December 23, 1921.

tively high resistance in order to produce as little drain on the circuit as possible and must be small, in order not to produce an appreciable change in the grid circuit characteristics. They are thus necessarily fragile.

A drawback of the series connection consists in the use of large iron resistances which must control the total potential variation of the whole powerline. Such resistances are very large and cumbersome. As is well known, when the current is cut in, iron resistances have first a very low resistance. It the iron resistances rise too slowly to their proper value, then the tubes will be overheated duringthis period of time and their life will be reduced.

The present invention eliminates this drawbackby connecting a resistance in parallel with the individual heating filaments or parallel with a group of heating filaments. The resistances in parallel with the individual tubes or with the groups of tubes perform two functions. First, in the case of the burn ing through of a tube, they limit the potential of the associated apparatus, so that the switch (not shown) and the grid-potentiometer are not endangered. Permanent resistances may serve for thispurpse. If, however, the resistances are made variable so that their value may be made lower than is warranted by the maximum potential on the tube apparatus, then the output of the tube apparatus may be regulated." The series connection of the heating filaments with resistances connectediu parallel results in a slight increase inthe heating current consumption as compared with the purely series connection. However, decidedly less current is consumed than is the case with a purely parallel connection.

In accordance with the present invention, a further advantage is attained by the possibility of using relatively small iron ballast resistances. In view of the fact that the potential applied to the tube islimited by the parallel resistance, the potential variations will also be only slight. For each tube or. for each group of tubes, a plurality of separately operating small iron resistances may be connected in the circuit, These re- 10 sistances are only very slightly sluggish and will quickly reach their proper value.

The drawing represents an embodiment of the present invention in a circuit arranges ment; R are the cathode tubes, E the small iron resistances, P, the grid potentiometers, V the series resistance, and W the variable parallel resistances. The power line poten tial is applied at the terminals N and N 7 Having described my invention, what I claim is:

1. In an arrangement for feeding cathode tubes, a plurality ofsets of cathode tubes, all tubes in said arrangement having their filaments connected in series, each set comprising at least one tube, a resistance connected across any set for limiting the potential across said set to a safe value for apparatus connected across said set if the filament in said set should be destroyed.

2. In an arrangement for feeding cathode tubes from power lines, a plurality of cathode tubes comprising two groups having their 7 filaments connected in series anda resistance connected in parallel with the filaments of a group of said tubes, said resistance being of such value as to limit the potential drop across it to a value which will not injure apparatus connected in parallel with one of the filaments of said group if said filament should be de- 'stroyed.

' 3. In an arrangementfor feeding cathode tubes, a plurality of sets of cathode tubes, all

tubes in the arrangement having their fila ments connected in series, each set comprising at least one tube, and means whereby the potential across any set is limited to a safe value for apparatus connected across said set if a filament in said set should be destroyed.

4. In an arrangement for feeding cathode tubes from power lines, a plurality of cathode tubes having their filaments connected in series, a small ballast resistance connected in series with the filaments of said tubes and a resistance connected in parallel with the series connection which includes said filaments and ballast resistance. v

5. In an arrangement for feeding cathode 7. In an arrangement for feeding cathode tubes, a plurality of sets of cathode tubes, all tubes in the arrangement having their filaments connected in series, each set comprising at least one tube, and means whereby any set has its own small ballast resistance which cooperates with said set to control the current :hereof.

8. In combination a group of vacuum tubes each tube having a plurality of electrodes including a control electrode and-a filament, means for connecting said filaments in series, a source of current, means connecting said filaments in series withsaid source through a control resistanceto provide approximate adjustment of the current therethrough, a ballast resistance in series with the filaments of said group of tubes, a resistance shunted across the filaments of said group of tubes, and means associated with said last named resistance to provide biasing potential for the control electrodes of at least one of-said tubes.

9. In radio apparatus a plurality of groups of thermionic tubes each having. input and outputelectrodes including a control grid and a filament, a source of current for the filaments of said tubes, means for connecting the filaments of said tubes in series with said source, a ballast resistance in series with each of said groups of tubes, a resistance in parallel with each of said groups of tubes, means for applying biasing potential to the control electrodes ofeach group of said tubes including means for connecting the control electrodes of each group to a point on one of said parallel resistances, and a protective resistance shunting the filaments and ballast resistance of each group of tubes. 7

AUGUST LEIB.

tubes from power lines, a plurality ofcathode tubes having their filaments connected in series, a small ballast resistance connected in series with the filaments oftwo of said tubes, and a resistance connected in parallel with the ballast resistance and the filaments of said two tubes only.

' 6. In an arrangement for feeding cathode tubes, a plurality of sets of cathode tubes, all thetubes in the arrangement having their filaments connected in series, each set comprising at least one tube, any set having its own small ballast resistance connected in series with said set and having a resistance con nected in series with said set and having a resistance connected in parallel with said set and its ballast resistance. 

